What Are the Side Effects of Taking Iron Tablets?

iron supplements
Side effects of taking iron tablets include constipation, dark stools and stomach upset

Iron is an essential mineral your body needs to produce hemoglobin, which is a red blood cell protein responsible for carrying oxygen from your lungs to other parts of your body. Iron also plays a significant role in hormone production and the overall of your nervous system. 

When your body doesn’t have enough iron this can lead to iron deficiency and iron deficiency anemia. The reduced amount of oxygen in your body can cause fatigue, shortness of breath, dizziness, palpitations and headache.

Taking supplements in the form of iron salts and iron pills can help your body maintain healthy levels of iron. Iron supplements are generally safe if taken as advised by your doctor, and the dosage varies depending on how severe your condition is.

The most common side effects associated with iron supplements include:

How can you relieve the side effects of iron supplements?

  • Constipation and dark stools: Use a stool softener, increase your intake of water, fluids and fiber and include probiotics in your diet.
  • Stomach upset: Stomach upset can be controlled by taking your iron supplement in smaller amounts with meals or snacks, but not on an empty stomach. If this doesn’t work, switching to another form of iron is recommended.
  • Stained teeth: Mixing the iron tablet with water or juice and drinking with a straw helps avoid staining. Iron stains can also be removed by brushing teeth with baking soda or peroxide.
  • Metallic taste: Drinking water or chewing gum may help eliminate a metallic aftertaste.
  • Heartburn: Taking an iron supplement with food and avoiding it at bedtime can help reduce heartburn.

What causes low iron levels in the body?

An iron deficiency may be caused by:

What are the benefits of taking iron supplements?

There are several benefits to taking iron supplements. They may: 

What to do before taking iron supplements

Before starting to take iron supplements, talk to your doctor if you:

Other precautions to take include the following:

  • Keep iron pills away from children to avoid the risk of iron overdose and iron toxicity. 
  • If you forget to take a dose, just skip it and then resume your regular dosing routine. Do not double dose.


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How to take iron supplements effectively

Here are some tips to ensure better absorption of iron supplements:

  • Take them on an empty stomach. If this causes stomach upset, switch to taking them with a small amount of food to avoid this problem.
  • Take them with vitamin C supplements or orange juice.
  • Don’t take them with milk, calcium-rich foods or calcium supplements, coffee or black tea. It’s best to consume these 2 hours before or after taking iron supplements.
  • Don’t take them with certain medications like antacids, tetracycline and fluoroquinolones. Wait 2 hours before taking either one.

What are different forms of iron supplements?

Iron supplements can also administered in the following ways:

  • Oral: Iron supplements can be taken orally in the form of pills and syrups. Ferrous salts used in oral iron supplements include ferrous sulfate, ferrous fumarate, ferrous gluconate and ferrous succinate. It may take up to 2 months for iron levels to become normal while taking oral iron supplements.
  • Parenteral: Parenteral iron supplements include iron dextran, iron sucrose, iron carboxymaltose and iron isomaltoside 1000. Iron supplement injections are given intravenously or intramuscularly when:
    • Oral iron supplements are not tolerated.
    • Absorption is compromised by illnesses.
    • You cannot swallow.
    • You have an underlying inflammatory condition, such as inflammatory bowel disease or kidney disease.
    • The level of hemoglobin needs to be increased quickly before elective surgery, post-operatively, post-transfusion or post-partum.

How long should you take iron supplements?

For most people, hemoglobin and iron levels usually return to normal after 2 months of iron therapy. In some cases, however, iron supplements may have to be continued for another 6-12 months. 

Your doctor will determine how long you need to take iron supplements based on regular blood tests that measure your body’s iron levels.

Harpar JL. Iron Deficiency Anemia Treatment & Management. Medscape. https://emedicine.medscape.com/article/202333-treatment

National Health Service. Ferrous Fumarate. https://www.nhs.uk/medicines/ferrous-fumarate/